We've camped in various rv's in our "winters" down south...
and while some rv's are truly all season IF you are running your furnace,
if freezing temps you have to consider a few things:
for sure a heated water supply line ,
possibly a SAFE auxillary heater in the basement areas,
or at least a 200 watt light bulb to generate some warmth down there...
go to youtube and do a search for winter camping to get some great ideas (and some, not so great